S, s-bis(ethylxanthoyl) o-ethyl trithiophosphate



Patented Feb. 9, 1954 UNITED STATES PATEL '1 OFFICE S,S-BIS(ETHYLXANTHOYL) O-ETHYL TRITHIOPHO SPI-IATE No Drawing. Application April 21, 1953, Serial No. 350,241

1 Claim.

in an inert organic solvent such as benzene. In practice, sodium ethylxanthate is preferably employed as the alkali metal xanthate reactant.

In carrying out the reaction, the O-ethyl thiophosphoric dichloride and sodium ethylxanthate are dispersed in the solvent and the resulting mixture heated for a period of time at a temperature of from 40 to 80 C. In practice, it is sometimes convenient to operate at the boiling temperature of the reaction mixture and under reflux. Since the desired product has a tendency to decompose at temperatures in excess of 80 C., reaction temperatures substantially in excess of 80 C. for any appreciable period of time are to be avoided. Upon completion of the reaction,

'the mixture may be distilled under reduced pressure at gradually increasing temperatures up to a temperature of 80 C. to separate low boiling constituents and to obtain as a residue S,S-bis- (ethylxanthoyl) O-ethyltrithiophosphate The O-ethyl thiophosphoric dichloride employed as a starting material in the abovedescribed method. may be prepared by reacting at least one molecular proportion of phosphorus thiochloride (P8813) with one molecular propor tion of ethanol. In carrying out the reaction, the alcohol is added portionwise with stirring to the phosphorus thiochloride. The reaction takes place readily at temperatures or from 020 C. The reaction is somewhat exothermic, temperature being regulated by the rate of contacting of the reactants and by the addition and subtraction of heat, if required. Upon completion of 2 the reaction the mixture may be fractionally distilled under reduced pressure to separate the desired O-ethyl thiophosphoric dichloride. The latter is a water-clear liquid having a boiling point of 68 C. at 20 millimeters pressure.

In a representative operation, 10 grams (0.07 mole) of sodium ethylxanthate was added to 5 grams (0.028 mole) of O-ethyl thiophosphoric dichloride dispersed in benzene and the resulting mixture heated for 1.25 hours at the boiling temperature or the reaction mixture and under reflux. The mixture was then filtered and the filtrate concentrated by distillation under reduced pressure to a temperature up to 80 C.

to obtain as a residue the desired S,Sbis(ethylxanthoyl) O-ethyl trithiophosphate product. The latter is a viscous oil having a density of 1.180 at 11 C.

The new S,S-bis(ethylxanthoyl) O-ethyl trithiophosphate product is effective as a parasiticide and adapted to be employed for the control of a wide range of agricultural and household pests such as flies, mites, aphids, beetles and cockroaches. For such use, the compound may be dispersed on an inert finely divided solid and employed as a dust. Also, such mixtures may be dispersed in water with the aid of a dispersing and wetting agent and the resulting aqueous suspensionsemployed as sprays. In other procedures, the new product may be employed in oils, as a constituent in oil in water emulsions, or in water dispersion with or without the addition of emulsifying, wetting or dispersing agents. Suitable concentrations of the toxicant in dusts are in the order of from about 0.1 to 10 percent by weight of the dust and in liquid suspensions from about 0.1 to 3 pounds per 100 gallons of the spray mixture.

application, Serial No. 203,771, filed December 30, 1950.

I claim:

S,S-bis(ethylxanthoyl) O-ethyl trithiophosphate.

HENRY TOLKMITH.

No references cited. 

